(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PB[Black to play and kill]AW[mm][nm][om][pm][mn][qn][rn][mo][po][ro][pp][qp]AB[ml][nl][ol][pl][ql][lm][qm][rm][ln][lo][mp][np][rp][oq][pq][qq][rq]
(;B[oo]C[This is the move that leaps to mind.]
(;W[on]
;B[no]C[White only has one eye.])
(;W[op]
;B[no]
;W[on]C[Still only one eye.])
(;W[no]C[However white can answer here.]
(;B[op]
;W[on]C[Three eyes.])
(;B[on]
;W[op]C[Black can do nothing.])))
(;B[no]C[So white's vital point must be black's - this is the
simple move that kills.]
(;W[on]
;B[oo])
(;W[oo]
;B[on]C[White can't capture this stone, so he's dead.])))